A braking system may slow a moving vehicle by converting its kinetic energy into heat energy. The heat is the result of friction between a rotating disc (rotor) and a pair of brake pads squeezing the rotor.
A brake pad may have a pad of friction material (also referred to as a friction pad, friction element, or friction puck) attached to a brake pad backing plate (e.g. a steel backing plate). Two such brake pads may be installed on opposite sides of a fixed hydraulic caliper that straddles the rotor. Applying the brake pedal may generate hydraulic pressure which moves the caliper's piston and forces the two brake pads to squeeze against the rotor.